Marine wildlife

Weedy Seadragon. Image source: Parks Victoria

Port Phillip Bay has a rich variety and wonderful diversity of marine and estuarine habitats.

What kinds of marine life are found in Port Phillip Bay?

The number of different species found in Port Phillip Bay is not known exactly, but it is thought to be around ten thousand. While Port Phillip Bay supports stable communities of mixed local species, it also supports a large diversity of migratory species which move into, out of and around the bay.

Fish

Port Phillip Bay supports a large range of fish species, some of which provide the basis for important commercial or recreational fisheries. These species mostly live on or close to the seabed (e.g. flathead) and are known as ‘benthic’ species. Other fish which move more freely (e.g. pilchards, Australian salmon) are known as ‘pelagic’ species. The fish in the bay vary in size from tiny sprats to very large predators (e.g. sharks). The most popular recreational fishing species in Port Phillip Bay are snapper, whiting and flathead.

Crustaceans

Unlike fish species which have backbones, crustaceans have bodies with an outer shell (exoskeleton). Some crustaceans (e.g. barnacles) spend most of their life attached to other objects (e.g. bottom of boats) while other species (e.g. crabs) are able to move around. Some crab species live in the intertidal zone and can survive out of the water for extended periods between tides. Other crustaceans (e.g. shrimps, bugs) are restricted to living close to the seabed, while some move more freely.

Spider crabs. Image source: J. Finn. Museum Victoria

Molluscs

Port Phillip Bay has a large range of diverse invertebrate (without a backbone) species known as molluscs. Molluscs are highly diverse in their structure, ranging from single sea-shell species (e.g. limpets) to bivalves (e.g. mussels, clams and oysters) and large mobile eight armed predators without shells (e.g. squids and octopuses). The great diversity is associated with variation in habitat preferences. One infamous mollusc resident of Port Phillip Bay is the beautiful but venomous blue ringed octopus, which sometimes hides under empty scallop shells or discarded bottles and cans. Many molluscs found in the bay are prized as edible seafood and form the basis of commercial and recreational fisheries (e.g. calamari squid).

Blue ringed Octopus. Image source: J.Finn. Museum Victoria

Sponges, starfish and other species

At the southern end of Port Phillip Bay, where it intersects with Bass Strait, there is a deep rocky canyon which is caused by an accelerated tide rushing in and out between the narrow confines of Port Phillip heads. This area has been assessed by scientists to be of international importance. It contains a high diversity of marine life associated with colourful sponge gardens that rival tropical coral reefs.

Port Phillip Bay also has many other interesting underwater species including microscopic plankton, large and small starfish, sea urchins, sandworms and even some cold water species of coral.

Birds

Up to 80 species of resident and migratory seabirds found in Victorian waters have been recorded in the waters of Port Phillip Bay. These are significant predators and scavengers of the aquatic life found in the bay. Some species such as albatrosses and petrels are rare or less frequent migratory visitors from the southern oceans. Others, such as terns, gulls, pelicans and gannets have significant local breeding colonies in or near Port Phillip Bay.

There is also a breeding colony of little fairy penguins that nests between the breakwater boulders at St Kilda in the north of the bay. The bay is an important feeding ground for the penguins which regularly travel from the large colony found on Phillip Island.

Australian Pelican. Image source: Parks Victoria

Marine mammals

The large navigation structures in Port Phillip Bay are not only useful for guiding ships, they have also been adopted as a resting place by large numbers of Australian fur seals which have taken up residence. Port Phillip Bay also supports a permanent population of bottle nosed dolphins, and is occasionally visited by southern right whales.

Fur seal. Image source: Parks Victoria

For further information about marine wildlife please refer to the following resources:

Port Phillip Bay Taxonomic Toolkit provides information, data, images and tools to help identify, document and monitor the rich marine animal life of the bay. It is the product of collaboration between the Victorian Government and Museum Victoria.

Fishes of Australia is a fantastic resource for information on Australia’s amazingly rich and diverse fish fauna – numbering about 5,000 species. Fish live in almost all aquatic environments in Australia – from the coral reefs and huge estuaries of the north, in the desert springs and fragile freshwater environments of the centre, to the cool environments of the south. This site contains information, images, videos, distribution maps and identification aids to our wonderful marine and freshwater fishes.